Brooke Mueller tried to put her ugly Christmas with Charlie Sheen behind her Monday night. After a cocktail party at her mother’s, Mueller went to the Caribou Club in Aspen, where she kept her distance from Paris Hilton, Doug Reinhardt and Gerard Butler. “Brooke was low-key,” a source tells E! News. “But she stayed until closing time.” Meanwhile, Sheen’s ex-wife, Denise Richards, was denying she trotted out her two daughters by Sheen for a photo op. “I genuinely love to be with my girls and don’t have a nanny raising them,” she tweeted. “They are my No. 1 priority and always will be.”